.[1] Momentum transfer across the wind-driven breaking air-water interface under strong wind conditions was experimentally investigated using a high-speed wind-wave tank together with field measurements at normal wind speeds. An eddy correlation method was utilized to measure roughness length and drag coefficient from wind velocity components measured by laser Doppler and phase Doppler anemometers. As a result, a new model for the roughness length and drag coefficient was proposed for predicting momentum transfer across the sea surface under both normal and strong wind conditions using the universal relationship between energy and significant frequency of wind waves normalized by the roughness length. The model shows that the roughness length and drag coefficient are uniquely determined at all wind speeds by energy and significant frequency of wind waves, and they can be given against U 10 only from the measurements of the wave parameters and one-point mean air velocity in the logarithmic law region. Citation: Takagaki, N., S. Komori, N. Suzuki, K. Iwano, T. Kuramoto, S. Shimada, R. Kurose, and K. Takahashi (2012), Strong correlation between the drag coefficient and the shape of the wind sea spectrum over a broad range of wind speeds, Geophys.
Alkaline hydrolysis liberated ferulic and diferulic acid from polysaccharides of the Avena coleoptile (Avena sativa L. cv. Victory I) cell walls. The amount of the two phenolic acids bound to cell walls increased substantially at day 4–5 after sowing, when the growth rate of the coleoptile started to decrease. The level of these acids was almost constant from the tip to base in 3‐day‐old coleoptiles, but increased toward the basal zone in 4‐ and 5‐day‐old ones. The ratio of diferulic acid to ferulic acid was almost constant irrespective of coleoptile age and zone. An increase in the amount of ferulic and diferulic acids bound to cell wall polysaccharides correlated with a decrease in extensibility and with an increase in minimum stress‐relaxation time and relaxation rate of the cell wall. The level of lignin in the cellulose fraction increased as coleoptiles aged, but this increase did not correlate with changes in mechanical properties of the cell walls. These results suggest that ferulic acid, ester‐linked to cell wall polysaccharides, is oxidized to give diferulic acid, which makes the cell wall mechanically rigid by cross‐linking matrix polysaccharides and results in limited cell extension growth. In addition, it is probable that the step of feruloylation of cell wall polysaccharides is rate‐limiting in the formation of in‐termolecular bridges by diferulic acid in Avena coleoptile cell walls.
The functional properties of heat-induced egg white gels were investigated at five pH values. Textural characteristics were determined using the Instron Universal Machine. Hardness, elasticity, cohesiveness, chewiness, and fracturability were maximum at pH 11. Hunter L values were maximum at pH 5 and 7. Microstructure studied with electron microscopy was distinctly different at the five pH values. Alkaline gels showed a fine ordered network that might have contributed to excellent textural characteristics. Water-holding capacity (WHC) was high at alkaline pH, but decreased with addition of 2-mercaptoethanol, suggesting that disulfide bonds were important in egg white gels. Sodium dodecyl sulfate (SDS) improved WHC at pH 7 and 9. No significant correlation was observed between textural profiles and WHC.
Heat and momentum transfer across the wind-driven breaking air–water interface at extremely high wind speeds was experimentally investigated using a high-speed wind-wave tank. An original multi-heat-balance method was utilized to directly measure latent and sensible heat transfer coefficients. The results show that both heat transfer coefficients level off at low and normal wind speeds but increase sharply at extremely high wind speeds. The coefficients have a similar shape for wind speeds at a height of 10 m. Therefore, the wind speed dependence on the latent and sensible heat transfer coefficients can be represented by that of the enthalpy coefficient even in the extremely high-speed region. To show how significantly the drag and enthalpy coefficients affect the intensity of tropical cyclones, the coefficients were applied to Emanuel’s analytic model. The analytic model shows that the difference between the present laboratory and conventional correlations significantly affects the maximum storm intensity predictions, and the present laboratory enthalpy and drag coefficients have the remarkable effect on intensity promotion at extremely high wind speeds. In addition, the simulations of strong tropical cyclones using the Weather Research and Forecasting (WRF) Model with the present and conventional correlations are shown for reference in the appendix. The results obtained from the models suggest that it is of great importance to propose more reliable correlations, verified not only by laboratory but also by field experiments at extremely high wind speeds.
The most frequent FGID was IBS in both overlapping and non-overlapping FGID patients. IBS and FD were the most frequent combinations in overlapping FGID. Most cases of FD are possibly parts of functional bowel disorders.
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